The present invention relates broadly to flexible rubber hoses for low, medium, or, particularly, high pressure applications, and more particularly to a construction therefor which is of a compact design.
Flexible rubber hose is used in a variety of hydraulic and other fluid transfer applications for conveying fluid pressures which for “high” pressure applications typically range from about 4000 psi (28 MPa) to 8000 psi (55 MPa) or more. In basic construction, hoses of the type herein involved typically are formed as having a tubular, innermost inner tube or core surrounded by one or more outer layers of a braided or spiral-wound reinforcement material which may be a metal or metal-alloy wire or a natural or synthetic fiber. The reinforcement layers, in turn, are protected by a surrounding outermost jacket or cover which may be of the same or different material as the inner tube. The cover also provides the hose with increased abrasion resistance.
In the case of “rubber,” as opposed to thermoplastic, hose constructions, the inner tube, may be provided as formed of a vulcanizable natural or, more typically, a synthetic rubber material such as Buna-N or neoprene. Such material or blend may be conventionally extruded and cooled or cured to form the inner tube. As is detailed in U.S. Pat. Nos. 3,116,760; 3,159,183; 3,966,238; and 4,952,262, if necessary, the tube may be cross-head extruded over a mandrel for support, or otherwise supported in later forming operations using air pressure and/or reduced processing temperatures.
From the extruder, the inner tube may be delivered through a braider and/or a spiral winder for its reinforcement with one or more surrounding layers of a wire and/or fibrous material or blend such as a monofilament, yarn, cord, yarn-wire composite, or roving. As is described in Japanese (Kokai) Publ. No. 10-169854 A2, Canadian Patent No. 973,074, and U.S. Pat. Nos. 3,654,967; 3,682,201; 3,790,419; 3,861,973; 3,905,398; 4,007,070; 4,064,913; 4,343,333; and 4,898,212, these reinforcement layers are applied under tension and typically may be formed of an interwoven braid or a spiral winding of a nylon, polyester, polyphenylene bezobisoxazole, polyvinyl acetate, or aramid yarn, or a high tensile steel or other metal wire. A relatively thin bonding or other interlayer of a vulcanizable rubber may be extruded or otherwise applied between each of the reinforcement layers to bond each layer to the next layer.
Following the braiding, winding, or other application of the reinforcement layers and the interlayers, an outer cover or sheath optionally may be applied. Such cover, which may be formed as a cross-head extrusion, a moisture-cured or solvent-based dipped coating, or a spiral-wound wrapping, typically comprises an abrasion-resistant synthetic rubber or a thermoplastic such as a polyurethane. Following the application of the cover, the hose construction so-formed by be heated to vulcanize the rubber layers and thereby consolidate the construction into an integral hose structure. Representative hose constructions, as well as manufacturing methods and materials therefor, are shown in U.S. Pat. Nos. 3,921,674; 3,953,270; 3,994,761; 4,104,098; 4,238,260; 4,759,388; 6,037,025; 6,474,366 and 7,143,789.
In normal use, such as in mobile or industrial hydraulic applications, hoses of the type herein involved may be exposed to a variety of environmental factors and mechanical stresses which cannot always be predicted. Of utmost importance to the integrity and performance of the hose is that a strong bond is achieved between the constituent parts thereof. However, while it is important to bond these parts together, it is also important that the hose not be made overly stiff so as to make it prone to kinking or fatigue or otherwise useable for certain applications.
In view of the foregoing, it will be appreciated that hose constructions must exhibit a demanding balance of chemical and physical properties. Indeed, as commercial applications for hoses continue to increase, it is believed that improvements in hose constructions would be well-received by numerous industries. Especially desired would be a construction which is flexible and light-weight, yet resistant to external stresses in a variety of mobile and industrial applications.